Ceteris Paribus
by Equinoxole
Summary: Reborn is a perfectionist, among all the other things that he is which is why, it is only inevitable that he'd try to control that one independent variable, Tsunayoshi, just to balance out everything with his dependent variable. Ceteris Paribus everyone.
1. Chapter 1

It was the first time in a long while that Reborn had something akin to affection, care, and interest playing in his eyes and not lust, all of it was for the too-feminine-to-be-a-boy cashier named Tsunayoshi.

With every step that Reborn took, the menacing aura he exudes keeps getting larger and larger as he remembers the reason he is out of his armchair, with him supposed to be sipping on a cup of espresso, and instead, here he is, going to a damned pharmacy just to buy an equally damned pregnancy test kit, of all things!

He inhaled slowly from his nose and let it all out through his mouth, trying to calm himself lest he starts shooting the neighborhood down because his _angel_ of a leader has gone through a fit, which happened minutes ago.

 _Being a hitman, and the greatest at that, Reborn only had a few amount of time spent in peace and he clearly doesn't want those moments going to waste which is why, it was only understandable that Skull, the stupid lackey who was noisily running down the hall, lays motionless on the doorway of the study, where Reborn was previously enjoying his espresso, because the greatest hitman in the world has thrown a pencil straight into one of Skull's pressure points._

 _Reborn was about to go back to his peaceful lounging when their Boss, Luce, has graced him with her presence which was, of course, welcomed but not entirely appreciated at the moment._

 _"Ara? What happened to Skull, Reborn?" Luce softly inquired while patting her belly softly, seeing as she was already 5 months pregnant._

 _"His stupidity must have gotten the better of him. Why?"_

 _"Is that so? Aw, he was supposed to run me some errands but since he's not capable of doing those, I'm afraid you'd have to do it in his stead, Reborn. Is it okay?" Luce said in her sickly sweet voice._

 _Reborn stared._

 _Stoically._

 _Luce kept smiling._

 _Blindingly._

 _Skull is still lying on the floor._

 _Motionlessly._

 _Seeing that Skull might be waking up hours later, or maybe tomorrow, Reborn should really do what Luce wants because even if he is a ruthless, merciless, demon of a hitman, it's not in him to let a pregnant woman who's already having troubles waddling around the house, do something._

 _"What is it, Luce?"_

 _Luce beamed._

 _"Yay! Can you buy a pregnancy test kit for me?"_

 _Reborn blinked slowly._

 _"Is this for Lal, or any of your friends?" Reborn said carefully. It's better to test the waters first when you're speaking with a pregnant, moody woman._

 _"What are you talking about, Reborn? Of course it's for me!" Luce even had the gall to look affronted._

 _Reborn lowered his fedora to hide the glare that he was tempted to show to Luce, but he didn't, because if he did, the woman might do what she did last time when she mentioned that she took the Verde's humanoid (which acts like their housekeeper), and of course, Luce being her, had been chatting with the human-like, however monotone the robot might be, and apparently, they decided to go to an onsen_ ("I fear that I may only be capable of accompanying you on the sidelines, Luce-sama, for I am a robot" _the humanoid has been repeating for a long time already, and, as always, Luce will laugh good-naturedly and reply with "_ Oh, you! I know you're just shy of letting someone see you naked. You're a foreigner, no? That's why you're awkward with the language and you speak flatly. Who taught you the term robot? The correct term is 'human', okay? Human! Remember that! _") To strengthen their bond as women-left-in-the-house-for-too-long._

 _(the protests of "_ I am actually a robot and therefore, genderless, Luce-sama _" of the robot was ignored) and it suddenly started convulsing, sparks flew around her (not the good kind, like in those movies but the I-was-actually-a-robot-that-was-dragged-on-an-onsen-trip-because-my-master-didn't-believe-me-and-she-wasn't-informed-by-my-creator-that-I-was-a-robot-because-Verde-sama-thought-it-was-obvious-and-Luce-was-not-an-idiot kind of sparks) and suddenly, Luce believed that the nanny was really saying the truth and she really was a robot, so, she told Verde that their nanny was no more, and Verde, being the sentimental creator, sent her a nasty glare and was about to ask her questions of how exactly did their housekeeper got destroyed, when Luce cried, sat down on the floor, and she tried to roll on the floor, with her protruding belly, and they were thankful enough that Fon was quick at stopping the woman from injuring herself and the baby but still, she gave all of the Arcobaleno the shock of their life._

 _Reborn shuddered inside his mind at the thought of a deformed baby because the mother was moody enough to roll on the floor. He sighed and looked at Luce._

 _"Why, pray tell me, do you need this pregnancy test kit, Luce?" he said while keeping a firm grip on his patience._

 _"Well, you know. My belly has been sticking out for some time already and… I think I might be pregnant." As she finished her sentence, Luce was in the verge of tears._

 _"Luce." Reborn called to her without looking at her because with his expression right now, he doesn't trust that Luce won't run away in fear._

 _"Yes?" she answered with a trembling voice._

 _"You ARE pregnant."_

 _…_

 _The room was silent. No one spoke. And suddenly…_

 _"YOU CAN'T JUST SAY THAT! (The vase was thrown at Reborn, which he easily dodged) YOU THINK YOU KNOW EVERYTHING ABOUT A WOMAN, HUH? WHAT, BECAUSE YOU'RE ALSO A DOCTOR? (The ashtray crashed behind Reborn as Luce approached the paperweight) I MAY JUST BE GETTING FAT, YOU KNOW? (Luce struggled to pick the chair up, and Reborn decided that enough was enough. There was no winning in this messed up conversation, however one-sided it may be)._

 _"Luce, stop. I will buy what you need."_

 _Luce stilled and her eyes watered. "Really? You'd do that for me, Reborn?"_

 _"Yes, now go and rest." His fate was sealed._

 _"Yay! Thanks Reborn!" was her parting words as she skipped (how that was possible with her being pregnant was beyond him)._

 _Reborn calmly walked out of the study room but, not before giving Skull a kick on his side. Hearing some bones crack was enough to place the smirk back on Reborn's face._

And here he was, outside the pharmacy to buy something that is not actually needed at this point of time. Reborn adjusted his fedora before entering the establishment.

"W-welcome!"

Reborn looked at the direction of where the voice came from and all he saw was a brunet with unbelievably gravity-defying hair, doe eyes with the color of brown dusted with gold, and _yes_ , Reborn thought, _he'd do this kid_.

And with that thought, he sent the brunet one of his disarmingly sexy smirks.

To say that Reborn was ecstatic was an understatement when he saw how the brunet reddened after being on the receiving end of his attention.

 _This will be fun._


	2. Chapter 2

Sawada Tsunayoshi was not having the best time of his life right now.

 _Well, seeing as I woke up tangled in various limbs, I doubt anyone would count that as a great start of the day._ Tsuna thought drily as he tried to scratch his neck.

Wait…

He woke up tangled up in various limbs…

Woke up tangled in various limbs…

 _Woke up…_

 _Tangled…_

 _Various limbs…_

 **H-HIIIIIIIIIEEEEEEEEEEE!**

 _Oh my god it sounds like I had an orgy or something! Maman didn't raise me to be that risky… Well, sure. She_ ** _did_** _encourage me to have an active sex life…_ Tsuna trailed off in his internal monologue as he remembered the moment she first introduced Gokudera and Yamamoto to her…

* * *

 _Tsuna, Yamamoto, and Gokudera were on their last year in middle school when they became close friends. Tsuna, being too tired of his friends' nagging him about meeting his Mom._

 _"Juudaime, when will we meet the glorious presence of your regal mother who—"_

 _"We're not of royal blood, Gokudera-kun". Tsuna interrupted Gokudera before he starts praising his Mom, her beauty (for capturing the attention of Tsuna's father whose genes were necessary to create Juudaime; these are Gokudera-kun's words), her arms (for never getting tired of caressing her belly to ensure the fetus form of Juudaime that he is safe, and of course for holding herself up while doing various positions in creating Juudaime; here, Gokudera receives a whack on his head, courtesy of Yamamoto for reasons you'd know later, while Tsuna, innocent he may be, knows what they are talking about and just starts pathetically flailing his arms on the sidelines with his face being colored in an unhealthy shade of red)._

 _How, you ask, did pure, little, innocent Tsu-kun get what Gokudera was talking about instead of just standing on the side and tilting his head cutely, like what everyone expects his reaction would be when the topic strays into something sexual? Tsuna might have really stayed that way if Nana herself didn't bring upon herself the development issues of her son._

 _All Nana did was force upon her Tsu-kun's hands a large box filled with_ _ **p-p-po-porn**_ _since she said she was a bit worried that Tsu-kun hasn't started washing his sheets on his own which means he hasn't had a wet dream yet, so what better way to catch up to the development chart than forcing his body to produce some… stuff that are necessary for the future humans, ne?_

 _Then she proceeded to lock Tsuna in his own room and said not in her ditzy tone, instead, using a threatening-mom tone, "If I don't hear you suppressing a moan, Tsunayoshi, I swear to your father who became a star that I'd go to a red light district somewhere to get someone to do the stuff you refuse to do, okay? So hurry up, darling, Maman loves you whatever gender the magazine that made you produce something was featuring, okay? Oh, this is also a great way of knowing what your sexuality is, huh?" and she continued to merrily skip downstairs, leaving Tsuna, again, with an unhealthy shade of red on his face (this might really be detrimental to his health, rather than make him develop into someone healthy)._

 _At the end of the day, Nana was squealing happily because there Tsuna was, on the foot of the stairs, his head bowed down low, with his sheets crumpled into a ball on his right hand, while his left was holding a BL manga that his mom has graciously supplied him earlier._

 _And that's how Nana was just friendly if Kyoko or Haru came over, because for her, no need to get too attached for if she did, she might want them as daughters-in-law but that's impossible already which is why, Tsuna is getting a bit scared of her mom's reaction if she introduces Gokudera and Yamamoto._

 _Speaking of Yamamoto, he's also the one who's ecstatic to meet his mom for reasons unknown to him… or he chose for the topic to be unknown to him. He once had asked Yamamoto why he shared the same nature with Gokudera when they're talking about his mom._

 _Yamamoto being Yamamoto, smiled good-naturedly and said, "Well, it's just I wanted to see what moms are like at this age because mine died earlier."_

 _Tsuna was stupefied and a bit guilty that he didn't know this about Yamamoto, he was about to apologize for throwing an insensitive question when he heard Yamamoto mutter under his breath…_

 _"I'd like to meet her and see if she could pass as my Father's lover and my stepmom, even though it means holding back my feelings for you Tsuna, at least, incest might be a bit challenging and fun huh? And it also makes playing house a little bit easier since we'd live under the same roof."_

 _Tsuna slowly backed away as Yamamoto started to chuckle darkly to himself._

 _I guess, the reason Tsuna could still talk to Yamamoto right now without awkwardness was because his brain had erased those memories for his sanity's sake._

 _Anyway, the day that Tsuna dreaded has arrived, and here they were, standing right outside the door of his house. Tsuna's hand hovered over the doorknob, unsure if he should go through this undoubtedly humiliating event, or if he should just turn back and drag his friends to the cemetery then sob his eyes out and tell them that his family actually died long ago and he only had the courage to tell them now because he was afraid they might look at him with pity._

'Hm… That seems like a good idea', _Tsuna thought to himself._

 _He was about to go through with Plan B when the doors suddenly opened and out came Sawada Nana, in all her pink, frilly, and unbelievably girly apron._

 _"Ara? You're here Tsu-kun! Are these your… friends?" said Nana while wiggling her eyebrows up and down while saying the "friends" part._

 _Really, how subtle._

 _As always, Gokudera was the first one to jump into action. "G-good morning, Sawada-sama! I've heard a lot of good things about you, now I know where Tsuna-sama got his beauty from! The surveillance photos and videos doesn't do you justice!"_

 _"SURVEILLANCE?!" Tsuna shouted while showing a horrified face._

 _"Oh? That was you? Ah, I did feel like someone was stalking me, but, you know, I thought my fantasies just came true. Ah, I have always wanted to be a celebrity, with all those paparazzi following me around! My darling Iemitsu used to act like that, you know! Ah, good old days." Nana sighed dreamily as she recalled memories of her youth that Tsuna never really wanted to know._

 _"Yo, Sawada-san! I'm Yamamoto Takeshi! Wah, you really are pretty! You know, my father" Yamamoto proceeds to pull out a picture of his father, "he's the best sushi chef in Namimori! His name is Yamamoto Tsuyoshi! He graduated with a degree in culinary arts! He is also a sword wielder! He'd be the greatest husband, you know! He can cook, he can protect you in times of need, and he's very loyal!" Yamamoto continued to praise *coughmorelikegivingouthispopscough* his father._

 _"Well! Isn't that great!" Nana, ever the dense mom, replied good-naturedly._

 _"Yeah, want me to set you up with him?" Yamamoto's eyes sparkled._

 _Nana's smile froze._

 _Gokudera was rolling around, laughing._

 _Tsuna stood still and his eyes turned blank._

 _Nana broke the silence with her saying "Wait a minute, okay?" and she went inside the house._

 _Then she came back._

 _With a pan._

 _And promptly slapped Yamamoto upside the head with it._

 _"You child! Do you want me to commit adultery! I've got a husband and seeing as you're the child of this Tsuyoshi, he's got a wife also! What are you even suggesting?!" Nana ranted like a mom. Well, technically, she is a mom but she doesn't act like it at times._

 _At this point, Yamamoto knows he has fucked up so he better fix this now._

 _'Time to play the kicked puppy act' thought Yamamoto._

 _"I'm so sorry, Sawada-san! It's just that, my mom died and I have been looking for the gentleness of a mother, I'm so sorry, I'm so sorry!" Yamamoto chanted._

 _Nana dropped the pan and ran dramatically to Yamamoto, which wasn't actually necessary since Yamamoto was so close, like a step away, but still, Nana did and hugged Yamamoto._

 _"Aww, don't cry! You can call me 'Maman' okay? I'll be your mom! Let's forget all about this misunderstanding, okay? Why don't we go in?"_

 _Nana proceeded to usher Yamamoto in, while Gokudera started shaking Tsuna's shoulders because Tsuna had this frozen expression on his face and he wasn't moving._

 _Really, Tsuna should screen the people he'd introduce to his mom first before going through with the whole meet and greet thing._

 _The brunch they had went by smoothly, with Yamamoto and Gokudera on their best behaviors because they were in the presence of Sawada Nana, and both males knew that you'd have the court the parents first before the child himself._

 _At the end of the visit, Nana gave them both a card, with 10 circles on it but the first circle already had a stamp mark._

 _"That's a sign that you cleared level 1 for Tsu-kun's heart, okay? Good luck, both of you! Oh! There's a little gift from me at the back of the card." Nana whispered hurriedly seeing as Tsuna was coming closer._

 _Both males flipped their cards and went red at what they saw._

 _In Gokudera's card was Tsuna, with cat ears tinted red at the tip, cream-colored suspenders and tail, all connected to a skimpy, also cream-colored shorts, his nose was drawn with black, resembling a cat's nose, and some whiskers on his cheeks. He was meow-ing to the camera, enough to lodge himself even deeper into Gokudera's M-Rated fantasies about him._

 _In Yamamoto's card, Tsuna was wearing dog ears, with the color blue as an outline, he was on a bed, with blue and white furry sheets, his lower body was covered but his torso-_ oh god his torso— _it was bare, some parts of it covered by the sheets which Tsuna was lifting up along with his had that's rubbing his eye._

 _"Come now, guys!" Tsuna shouted to them._

 _It took all Gokudera's and Yamamoto's willpower to stop themselves from getting totally hard right there and then. They were on residential land after all._

 _And that was how Nana Sawada ended up laughing on her own inside the house, thinking of the concept for her next stamp card productions._

* * *

Back to the present, Tsuna's problem is about how he should get up from this mess. He had both a literal and figurative _athlete's foot_ stationed on the juncture of his neck and collarbones, an arm circling his waist, grayish-white hair tickling his nose, and a hand positioned near— _too near_ —his thighs.

He doesn't want to hurt his friends by just bolting out of bed, but the idea was really tempting, seeing as how they invaded his personal space—if he even had any, to begin with—all the time.

Of course, Takeshi was the first one to offer himself as Tsuna's Dutch wife, and before Tsuna had the chance to decline, Hayato jumped down from the ceiling (where he was hiding while taking note of Tsuna's every move, looking out for harm coming towards Tsuna, and yes, taking some pictures of Tsuna for… security purposes because Hayato thinks he might miss any suspicious action while he blinks), and proceeded to beg Tsuna for the chance to sleep next to him to guard him even better.

And here they are now. All tangled up like they were in some sort of harem.

As Tsuna resigned himself to just staying there to avoid any injuries, a yellow ball of fluff entered from his window and cutely made its way to the bed.

"Hello Hibird" Tsuna whispered to the loyal subordinate of his friend.

Hibird gave a chirp back and tilted its head as if saying, _do you need help?_

Tsuna never had time to answer as Hibird positioned itself near Yamamoto's eyes, and promptly pecked his eyelids.

It bore instantaneous results as Yamamoto jumped out of bed and pull out his sword, while Gokudera, being the light sleeper he is, positioned himself in front of Tsuna, almost straddling him, while holding dynamites, and Tsuna, he… sat on the bed.

"Tenth! Are you alright?! Who's the bast-" Gokudera looked around the room to check who their assailant is, when Hibird chirped, _I swear Tenth, that bird smirked! Smirked at us!,_ and flew away.

As Gokudera continued to rant about Hibird, Yamamoto just laughs it off while Tsuna gently placates the bomber.

After the morning fiasco, they all prepared themselves as they went on their jobs and, yes, here Tsuna was, on his first job for the day which is at a pharmacy.

And he isn't prepared for this… _this_ man.

When the doorbell rang, he expected to see that white-haired man who gives (forces upon) marshmallows to him or, even the dark haired man with those feathers who doesn't really buy anything other than that one time where he bought strepsils, but really, all he does is glare a hole at Tsuna and leave when the guy with parabolas (Tsuna knows they're not umbrellas because when he told that mustache man to place his umbrellas in the rack, he looked so affronted and screamed that those were bloody parabolas).

But no, the one who entered was this human being—is he?—who's more like danger in mortal form.

 _'H-hieeeee! He's looking this way! W-what should I do?!'_ Tsuna shrieks as he reviews his How-to-talk-to-customers manual in his mind.

Ah!

"W-welcome!" he stutters out.

' _Good job, Tsuna. You have one potential customer who might actually buy something and you stutter ohmygod he would think the management is incompetent this slip up will lead to the destruction of the pharmaceutical company, you'll be fired Tsuna you have a family to— is… is that a smirk?'_ his rant ended in a question seeing as the customer is still inside and not going out of the establishment as he expected.

Tsuna mentally conjures the image of Kyoko-chan patting his head for a job well done and immediately blushes.

Then he squeaks as he suddenly remembers that he's staring straight into this customer while he blushed. ' _Ugh, now this man will think I'm a creep'._

Will this day get any better?

* * *

AN: Thank you so much for all the reviews, follows, and faves! After I posted this story I was so afraid of the reaction from you guys and I didn't go back for a week, and when I did, I found out I had no line breaks and I was like '?'. I was ashamed and now I'm late for an update I'm so sorry /insert I'm-a-newbie-author-this-is-my-first-story drama here/ anyway, thank you for waiting, I know this is late, and this may not be up to par but please bear with me lervyew oh and next chapter would be the interaction between the two /finally! R27/


End file.
